Depressed park windshield wiper system

ABSTRACT

In a preferred form, this disclosure relates to an actuating mechanism for oscillating a pair of windshield wipers across the windshield between inboard and outboard positions during running operation and for moving the wipers to a depressed park position when running operation is being terminated. The actuating mechanism comprises a housing means, an annular drive member rotatably supported by the housing means, a drive shaft rotatably supported by the housing means for rotation about its axis and drivingly connected with the drive member and a drive means operatively connected with the drive shaft for rotating the same. The actuating mechanism further comprises a crank assembly including a crank arm which is adapted to be connected with the wipers and a crank shaft eccentrically and rotatably supported by the drive member. The actuating mechanism additionally includes a shiftable means slidably supported on the drive shaft and the housing means and which is spring biased toward a first position in which it engages the crank assembly to lock the same against rotation relative to the drive shaft so that the crank assembly rotates with the drive member about the axis of the drive shaft during running operation of the wipers and which is shiftable by fluid pressure toward a second position in which it disengages the crank assembly and rotates the crank assembly in a direction opposite the direction of rotation of the drive shaft to increase the throw of the crank arm to move the wipers from their inboard position towards their park position.

United States Patent Carpenter [451 Dec. 12,1972

[54] DEPRESSED PARK WINDSHIELD WIPER SYSTEM [72] I Inventor: Keith H.Carpenter, Kettering, Ohio [73] Assignee: General. Motors Corporation,

Detroit, Mich.

[221 Filed: Oct. 21, 1971 [21] Appl. No.: 191,385

[52] U.S. Cl ..74/600, 15/2501? [51] Int. Cl. ..B60s' 1/24 [58] Field ofSearch ..74/600, 42, 75 l 5/250.l6,

[56] References Cited UNITED STATES PATENTS 3,ll5,599 12/1963 Ziegler..74/600X 3,242,520 3/1966 Carrolletal ..74/600X Primary Examiner-MiltonKaufman Assistant Examiner-F. D. Shoemaker AttorneyW. E. Finken et al.

[5 7] ABSTRACT In a preferred form, this disclosure relates to anactuating mechanism for oscillating a pair of windshield wipers acrossthe windshield between inboard and outboard positions during runningoperation and for moving the wipers to a depressed park position whenrunning operation is being terminated. The actuating mechanism comprisesa housing means, an annular drive member rotatably supported by thehousing means, a drive shaft rotatably supported by the housing meansfor rotation about its axis and drivingly connected with the drivemember and a drive means operatively connected with the drive shaft forrotating the same. The actuating mechanism further comprises a crankassembly including a crank arm which is adapted to be connected with thewipers and a crank shaft eccentrically and rotatably supported by thedrive member. The actuating mechanism additionally includes a shiftablemeans slidably supported on the drive shaft and the housing means andwhich is spring biased toward a first'position in which it engages thecrank assembly to lock the same against rotation relative to the driveshaft so that the crank assembly rotates with the drive member about theaxis of the drive shaft during running operation of the wipers and whichis shiftable by fluid pressure toward a second position in which itdisengages the crank assembly and rotates the crank assembly in adirection opposite the direction of rotation of the drive shaft toincrease the throw of the crank arm to move the wipers from theirinboard position towards their park position.

3 Claims, 7 Drawing Figures 4 r1 Wa mammal: 12 m2 [2 #2 r 40 W. 4 m%f- IM Z 0 [1] I 5 I 6; we. ma! m f *r l L K4? 7 2 3 F I ARM MANIFOLD :I I 1%1% I 11/;

5' Z02 I52 7 L i i OFF LOW HI ,1 7 INVENTOR.

ATTORNEY P'A'TE'N'TED nu: 1"2 m2 SHEET 2 0F 2 I ATTORNEY DEPRESSED PARKWINDSHIELD WIPER SYSTEM The present invention relates to a windshieldwiping system, and in particular to an actuating mechanism foroscillating windshield wipers across a windshield of an automotivevehicle between inboard and outboard positions during running operationand for moving the wipers to a depressed park position spaced from theinboard position when wiper operation is being terminated.

An object of the present invention is to provide a new and improvedactuating mechanism for oscillating a windshield wiper across the outersurface of a windshield between inboard and outboard positions duringrunning operation and for moving the wipers to a depressed park positionspaced from the inboard position when wiper operation is beingterminated and wherein the mechanism is of a relatively simple andeconomical construction.

Another object of the present invention is to provide a new and improvedactuating mechanism for oscillating a windshieldwiper across thewindshield between inboard and outboard positions during runningoperation and for moving the wiper to the depressed park position spacedfrom the inboard position when wiper operation is being terminated andin which the mechanism includes a housing means, an annular drive memberrotatably supported by the housing means, a drive shaft supported by thehousing means for rotation about its axis and drivingly connected to thedrive member, a crank assembly including a crank arm which is adapted tobe connected with the wipers and a crank shaft which is eccentricallyand rotatably supported by the drive member and a fluid operatedshiftable means slidably supported by the drive shaft and the housingmeans and which is shiftable between a first position in which itengages the crank assembly to lock the same against rotation relative tothe drive shaft so that the crank assembly rotates with the drive shaftabout the axis of the latter during running operation of the wipers anda second position in which it effects rotation of the crank assembly ina direction opposite the direction of rotation of the drive shaft toincrease the throw of the crank assembly and move the wiper to its parkposition upon their reaching their inboard position when wiper operationis being terminated.

Briefly, the above objects are accomplished by providing a novelactuating mechanism which, in the preferred and illustrated embodiment,comprises a housing means, an annular drive member rotatably supportedby the housing means, a drive shaft supported by the housing means forrotation about its axis and drivingly connected with the drive member, adrive means operatively connected with the drive shaft for rotating thesame and the drive member, a crank assembly including a crank arm whichis adapted to be operatively connected with the wipers and a crank shafteccentrically and rotatably supported by the drive member, and ashiftable means including a fluid operated piston'which is slidable onthe drive shaft and the housing means. The shiftable means, when nodifferential pressure is applied across the piston, is biased toward afirst position in which a slidable element cooperably engages a genevawheel drivingly connected to the crank shaft to effect rotation of thecrank shaft assembly with the drive shaft about the axis of thelatterduring running operation of the wipers. When running operation ofthe wipers is being terminated a differential fluid pressure is appliedacross the piston to shift the shiftable means from its first positiontoward a second position in which it cooperably engages the geneva wheelto effect rotation of the crank shaft assembly in a direction oppositethe direction of rotation of the drive member to cause the throw of thecrank to be increased to move the wipers upon reaching their inboardposition from their inboard position toward their park position.

The present invention further resides in various novel constructions andarrangement of parts, and further objects, novel characteristics andadvantages of the present invention will be apparent to those skilled inthe art to which it relates and from the following detailed descriptionof the illustrated embodiments thereof made with reference to theaccompanying drawings forming a part of this specification and in whichsimilar reference numerals or characters are employed to designatecorresponding parts throughout the several views, and in which:

FIG. 1 is a schematic view of a windshield wiper system embodying thenovelactuating mechanism of the present invention;

FIG. 2 is an axial cross-sectional view, with portions shown inelevation, of the preferred embodiment of the actuating mechanism of thepresent invention;

FIG. 3 is a view like that shown in FIG. 2, but showing different partsthereof in different positions;

FIG. 4 is a fragmentary sectional view taken approximately along line4-4 of FIG. 2;

FIG. 5 is an enlarged fragmentary sectional view taken approximatelyalong line 5-5 of FIG. 4;

FIG. 6 is a fragmentary sectional view like that shown in FIG. 3, butshowing different parts thereof in different positions; I

FIG. 7 is a schematic view of a control circuit means for controllingoperation of the actuating mechanism of the present invention.

The present invention provides a novel actuating mechanism for use in awindshield wiping system for oscillating a pair of windshield wipersacross the outer surface of a windshield between inboard and outboardpositions during running operation and to a depressed park positionspaced from the inboard position when wiper operation is beingtenninated.

As representing a preferred embodiment of the present invention, FIG. 1of the drawings schematically shows a windshield wiping system A forwiping a windshield 10 of an automotive vehicle (not shown). Thewindshield wiping system A comprises a pair of suitable or conventionalwindshield wipers 15 which are drivingly connected to drive pivots 16.The drive pivots are adapted to be rotatably supported by the bodystructure of the vehicle (not shown) at spaced locations adjacent thelower edge of the windshield 10.

The wipers 15 are adapted to be oscillated in tandem across the outersurface of the windshield 10 between inboard and outboard positions,designated by the letters I and O in FIG. 1 of the drawing, duringrunning operation and are adapted to be moved from their inboardposition I to a depressed park position P adjacent the lower edge of thewindshield 10 when running operation is being terminated.

The wipers 15 are actuated or oscillated between their inboard andoutboard positions and to their park position P by a novel actuatingmechanism 20 via a transmission linkage means 21. The novel actuatingmechanism 20 includes a rotatable crank assembly 23 having a crank arm24 which is rotated in the direction of the arrow 27. The transmissionlinkage 21 comprises a pair of crank arms 28 and 29 having one end fixedto the drive pivots 16 and the other end swivelly connected to a crosslink 30. The transmission linkage also includes a drive link 32 which isswivelly connected to the crank arm 24 at one end and the other end isswivelly connected to a ball 33 carried by one end of the crank arm 24(see FIG. 2). Rotation of the crank arm 24 in the direction of the arrow27 causes the transmission linkage 21 to be reciprocated to cause thewipers to be oscillated in tandem across the outer surface of thewindshield 10.

The crank arm 24 has an effective radius r during running operationwhich causes the wipers to be oscillated between their inboard andoutboard positions I and 0. When wiper operation is being terminated andthe wipers l reach their inboard position the throw or radius of thecrank arm is increased to r to cause the wipers to be moved to theirdepressed park position P.

The novel actuating mechanism further comprises a metal casting orhousing 40 having an opening 41 therein. The opening 41 has a firstdiameter portion 41a and a reduced diameter portion 41b adjacent itsupper end, as viewed in FIG. 2.

The housing means 40 supports a drive assembly 42. The drive assembly 42comprises a unidirectional DC electric motor 43 whose output or armatureshaft 43a is fixed to a worm 44. The worm 44 is in meshed engagementwith a worm gear 46 fixed to a drive shaft 48. As viewed in FIG. 2, thedrive shaft is rotatably supported adjacent its lower ends via a bearing50 carried by an end cap or plate 52 suitably secured to the housing 40at its lower end. The drive shaft 48 is also drivingly connected at itsupper end to an annular drive member or bearing cap 53 rotatablysupported by the housing 40 at its upper end. The drive shaft 48includes a non-circular portion 48a which is received in thecomplementary shaped opening 54 in the drive member 53 to provide adriving connection therebetween. The annular drive member 53 is held inabutting engagement with a shoulder 48b on the drive shaft 48 by asuitable nut 57. The drive shaft 48 and the annular drive member 53 areconcentric and when the electric motor 43 is energized the drive shaft48 and annular drive member 53 are rotated within the housing 40 aboutthe longitudinal axis of the drive shaft 48.

The crank assembly 23 is rotatably and eccentrically supported by theannular drive member 53. The crank assembly 23 comprises the crank arm24 which has one end thereof secured to a crank shaft 60, the crankshaft 60 being rotatably received within an eccentric opening 61 in thedrive member 53 and held against relative axial movement with respect tothe drive member 53 by a pair of retainer rings 62. The longitudinalaxis of the crank shaft 60 is spaced from, but extends parallel to thelongitudinal axis of the drive shaft 48. The crank assembly 23 furtherincludes a geneva wheel 63 which is drivingly connected to or fixed onthe lower end of the crank shaft 60. The geneva wheel 63 comprises aplurality of angularly spaced lobes 64 and slots or recesses 65. Therecesses 65 extend radially of the wheel and one of the lobes 64a has aradially extending, arcuately shaped recess or cut out 66 at its outeredge or periphery, and for reasons to be noted hereinafter.

The crank assembly 23 is adapted to be drivingly connected with thedrive assembly 42 by a shiftable means 70. The shiftable means 70comprises a piston which is slidably supported by the housing 40 alongthe opening portion 41a for linear movement toward and from the annulardrive member 53, but which is prevented from rotating relative to thehousing. To this end, the housing 40 includes an axially extending rib81 which is received within a notch 82 in the periphery of the piston 80to prevent the same from rotating relative to the housing 40.Alternately, the piston 80 and the housing 40 could be of a non-circularshape in order to prevent the piston 80 from rotating relative to thehousing 40. The piston 80 divides the housing 40 into upper and lowerchambers 84 and 85.

The piston 80 includes an annular seal 86 at its periphery for sealinglyengaging the inner wall of the housing 40. The piston 80 carries a shifttube 90 which is slidably supported on the drive shaft 48. The piston 80also has a plurality, four in the preferred embodiment, axiallyextending posts 94 which are equally angularly spaced and which areequally radially spaced from the axis of the drive shaft 48. A partialor C- shaped flat ring member 95 is secured to three of the posts 94 attheir ends remote from the piston and with the fourth post 94a beingequally spaced between the adjacent ends 95a of the C-shaped ring member95.

The shiftable means 70 further includes a collar which is slidablysupported by the drive shaft 48 for relative movement axiallytherealong, but which is prevented from rotating relative thereto. Tothis end, the collar 100 is drivingly connected to the drive shaft 48via a key and slot connection 102 which prevents relative rotationbetween the collar 100 and shaft 48, but allows the collar 100 to slideaxially therealong.

The shiftable means 70 is normally biased toward the position shown inFIG. 2, which is also the position of the parts during running operationof the wipers 15. The shiftable means 70 is biased to the position shownin FIG. 2 by a compression spring having one end in abutting engagementwith the bottom of the annular drive member 53 and its other end inabutting engagement with the collar 100. The spring 1 l0 biases thecollar 100 downwardly which in turn engages the shift tube 90 to biasthe same and the piston 80 to the position shown in FIG. 2. In thisposition, the collar 100 drivingly engages the lobe 64a of the genevawheel 63. To this end, the collar 100 has an arcuately and radiallyextending recess or notch 104 adjacent a peripheral portion thereofwhich is complementary in shape to the adjacent portion of the lobe 64aof the geneva wheel 63. The lobe 64a of the geneva wheel at its oppositeends 106 is tapered and the collar 100 at its ends 100a and 10% whichengage the ends 106 of the lobe 64a of the geneva wheel 63 arecomplementarily tapered so that the collar 100 is in wedged engagementwith the ends 106 of the geneva wheel 63 to drivingly connect the genevawheel 63 to the collar 100. When in this position, the drive shaft 48also functions, through the collar 100, to prevent rotation of the crankshaft 60 relative to the annular drive member 53 whereby the crank arm24 is caused to be rotated with the annular drive member 53 about theaxis of the drive shaft 48. When the crank arm is rotated about the axisof the drive shaft 48, the wipers are caused to be moved between theirinboard and outboard positions I and 0, respectively.

The shiftable means 70 is adapted to be moved upwardly from its positionshown in FIG. 2 towards its position shown in FIG. 3 when wiperoperation is being terminated. This upward movement of the shiftablemeans 70 toward the position shown in FIG. 3 is effected bycommunicating the chamber 84 with a vacuum source, such as the inletmanifold of the vehicle. The lower chamberk85 is vented at all times tothe atmosphere via port 120. When vacuum pressure is applied to thechamber 84 the piston 80 is caused to be moved upwardly in opposition tothe biasing force of the spring 110.

If the wipers are not in their inboard position I when wiper operationis being terminated the C-shaped ring 95 will engage the underside ofthe geneva wheel 63 as the crank assembly 23 and annular drive member 53continue to rotate. This engagement continues until the geneva wheel63moves clear of the C-shaped ring 95, which occurs when the wipers 15 arein their inboard position I. When the geneva wheel 63 is disengaged fromthe ring 95, the piston 80, ring 95 and collar 100 are moved upwardlyvia the shift tube 90. As the collar 100 moves upwardly it disengagesthe lobe 64a of the geneva wheel 63. However, prior to disengaging thelobe 64a of the geneva wheel 63 the post 94a on the piston will bereceived within slot 65 adjacent the upper side of the lobe 64a of thegeneva wheel 63, as viewed in FIG. 4. When the collar 100 disengages thegeneva wheel 63 the crank assembly 23 is free to rotate relative to thedrive member 53 and continued rotation of the drive member 53 and crankassembly 23 in the direction of the arrow 27 causes the geneva wheel 63to be rotated therewith and also in the opposite direction, as indicatedby the arrow 122. The geneva wheel 63 is caused to be also rotated inthe opposite direction due to the engagement with the stationary post94a which causes the geneva wheel 63 and crank assembly 23 to be rotatedin the direction of the arrow 122. The geneva wheel 63 sequentiallyengages the posts 94 as it is rotated by the drive member 53. When thedrive member 53 and the geneva wheel 63 have been rotated 180, after thewipers l5 reach their inboard position I, a cam 123, on the lobe 64a ofthe geneva wheel 63 will engage a park switch 125 to open the same anddeenergize the wiper motor 43. The park switch 125 is carried by thehousing 40.

During the relative rotation of the crank assembly 23 with respect tothe drive assembly 42 the throw of the crank arm 24 or effective radiusthereof is increased, as indicated by r This increase in the throw ofthe crank arm 24 causes the crank arm 24 to move the wipers 15 fromtheir inboard position I toward their depressed park position P via thetransmission linkage 21%..

Operation of the windshield cleaning system A will be described withreference to the schematic control circuit means or diagram shown inFIG. 6. The control circuit means includes a DC battery 150 having oneterminal connected via a wire or conductor 151 to ground G the parkswitch 125 for the wiper motor 43, the electric wiper motor 43 whichincludes an armature 158 and shunt and series field windings 160 and162, respectively, an ignition switch 164, a resistor 165, a manuallyoperable wiper switch 167 having stationary terminals 168 and 170 and amovable bridging member 172, a park switch relay 173 carried by thehousing 40 and a valve means 174 for selectively communicating thechamber 84 with either the atmosphere or the inlet manifold.

The wiper switch 167 could be of any suitable or conventionalconstruction and the movable bridging member thereof is movable betweenan off position, a low speed position and a high speed position. Thepark switch 125 includes a stationary contact 125a and a mobile contactl25b carried by a leaf spring 125c which is self-biased toward a closedposition in which the contacts 125a and 125k engage each other, butwhich is normally held in an open position by the cam 123 on the genevawheel 63 when the windshield wipers 15 are in their parked position P. b

When the operator of the vehicle desires low speed operation of thewindshield wiping system, he will move the bridging member 172 of thewiper switch from its off position to its low speed position, as shownby the dotted lines in FIG. 6. Movement of the bridging member 172 toits low speed position also causes the valve means 174 to be moved (thevalve actuator, not shown, is operatively connected with the bridgingmember 172) to its open position in which it communicates the atmospherewith the chamber 84 via conduit 175 with the chamber 84 in communicationwith the atmosphere the spring 110 biases the shiftable means towardsits first position, as shown in FIG. 2. However, since the geneva wheel63 is in engagement with a post 94 connected to the C-ring and islocated beneath the C-ring 95, the shiftable means 70 will remain in theposition shown in FIG. 3 until it is located between the spaced ends ofthe C-ring 95.

When the bridging member is in the low speed position, an electriccircuit is completed for energizing the park switch relay 173. Thiscircuit is from battery 150, wire 177, now closed ignition switch 164,wire 178, circuit breaker 180, wire 181, relay coil 173a, wire 182,stationary contact 168, bridging member 172, wire 183 to ground GEnergization of the park switch relay 173 causes the core l73b thereofto move the leaf spring c and its associated contact l25b intoengagement with the stationary terminal 125a to close the park switch125. The closing of park switch 125 completes circuits for energizingthe series and shunt field windings 162 and and armature of the wipermotor 43. These circuits are from battery 150, wire 177, now closedignition switch 164, wire 178, circuit breaker 180, wire 181, parkswitch 125, wire 185, series field winding 162, wire 194, motor armature158, wire 196 to ground G and from wire 185, shunt field windings 160,wire 200, stationary contact 170, bridging member 172, wire 183 toground G In the low speed position the shunt field windings 160 arefully energized. The completion of these circuits energizes the wipermotor 43 for low speed operation.

When the wiper motor is energized, it rotates the drive shaft 48 and thedrive member 53 in the direction of the arrow 27. Rotation of the drivemember 53 in this direction causes the crank assembly 23 to be alsorotated in this direction, but the geneva wheel 63 will rotate the crankarm 24 in the opposite direction due to its sequential engagement withthe posts 94. This opposite rotation of the geneva wheel occurs for thefirst 180 rotation of the annular drive member 53 and causes the throwof the crank arm 24 to be reduced and the wipers 15 to be moved fromtheir park position P toward their inboard position I. When the annulardrive member 53 has been rotated 180 the geneva wheel 63 will bepositioned between the ends of the partial C- ring 95 and thus thebiasing force of the spring 1 will move the collar 100 and thepiston 80downwardly from the position shown in FIG. 3 to the position shown inFIG. 2. As the collar 100 is moved downwardly it will engage the taperedends 106 of the lobe 64a of the geneva wheel 63 to lock the geneva wheel63 against rotation relative to the annular drive member 53 whereuponfurther rotation of the drive shaft 48 causes the drive member 53 andcrank assembly 23 to be rotated together and about the axis of the driveshaft 48 whereby the wipers are oscillated between their inboard andoutboard positions I and 0, respectively.

When the wiper switch bridging member 172 is moved from its low speedposition to its off position to terminate wiper operation, theaforedescribed circuit for the park switch relay 173 is broken, sincethe bridging member 17 2 disengages the stationary contact 168 in itsoff position. The wiper motor 43, however, remains energized until thewipers reach their park position since the park switch 125 isself-biased toward a closed position during running operation of thewipers l5 and since the cam 123 is disengaged therefrom, as shown inFIG. 3. The park switch 125 remains closed until the windshield wipermotor 43 moves the wipers to their park position at which time the cam123 on the geneva wheel will open the same to de-energize the circuitsto de-energize the wiper motor 43. Also, when the bridging member 172 ismoved to its off position, the valve member 174 is moved to its secondposition in which it communicates the inlet manifold with the chamber84. When this occurs the shiftable means is shifted from its positionshown in FIG. 2 toward its position shown in FIG. 3. If the windshieldwipers were not approximately in their inboard position I when thebridging member 172 is moved to its off position and the valve member174 is moved to communicate the inlet manifold with the chamber 84, theshiftable means 70 is prevented from being moved towards its upperposition, as shown in FIG. 3 due to the fact that the partial C-ring 95will engage the underside of the geneva wheel 63. Thus, the annulardrive member 53 and' crank assembly 23 remain locked together until thegeneva wheel 63 clears the partial C-ring 95, as shown in FIG. 2, atwhich time the wipers will be at their inboard position. When thisoccurs, the shiftable means 70 is shifted upwardly to disengage thecollar 100 from the geneva wheel 63 and to move a post 94a on the piston80 within the slot 65 in the geneva wheel 63. The continued rotation ofthe annular member 53.causes the crank shaft assembly 23 to continue itsrotation. However, the geneva wheel 63 due to its engagement with thepost 94a is caused to be rotated in the opposite direction in thedirection of the arrow 122. This increases the throw of the crank toradius r; and causes the wipers 15 to be moved from their inboardposition I towards their park position P. When the crank assembly hasbeen rotated 180, the cam 123 on the geneva wheel will engage the leafspring 1250 of the park switch 125 to separate the contacts 125a and125b to break the aforedescribed circuits and de-energize the wipermotor 43.

When the operator desires high speed operation, he will move thebridging member 172 of the wiper switch 167 to its high speed position,as indicated by the phantom lines in FIG. 6. Movement of the bridgingmember 172 to this position causes only the stationary contact 168 ofthe wiper switch 167 to be bridged. When in this position thehereinbefore described circuits for energizing the park switch relay 173and the series field windings 162 and armature 158 of the wiper motor 43are completed. The hereinbefore described circuit for energizing theshunt field windings to ground G is not completed, since the bridgingmember 172 does not bridge the contact 170 in the high speed position.When the bridging member 172 is moved to the high speed position, theshunt field windings 162 are energized via a circuit through resistor toground G whereby the shunt field windings are only partially energizedwhich causes the wiper motor 43 to operate at high speed, and in amanner well known to those skilled in the art. This latter circuit isfrom battery 150, wire 177, now closed ignition switch 164, wire 178,circuit breaker 180, wire 181, park switch 125 (which is closed whenrelay 173 is energized), shunt field windings 162, wire 200, resistor165, wire 202 to ground G The manner in which the actuating mechanism 20effects movement of the wipers 15 to their park position P when wiperoperation is being terminated and from their park position to theirinboard position I when wiper operation is being initiated is the samefor high speed operation as it is for low speed operation.

Although the illustrated embodiment thereof has been described in greatdetail, it should be apparent that certain modifications, changes, andadaptations may be made in the illustrated embodiment, and that it isintended to cover all such modifications, changes and adaptations whichcome within the spirit of the present invention.

What is claimed is:

1. An actuating mechanism for use in oscillating a windshield wiperacross the windshield between inboard and outboard positions duringrunning operation and for moving the wiper to a park position spacedfrom the inboard position when wiper operation is being terminatedcomprising: a housing means; an annular drive member rotatably supportedby said housing means; a drive shaft supported by said housing means forrotation about its axis and drivingly connected to said drive member; adrive means operatively connected with said drive shaft for rotating thesame and said drive member; a crank assembly including a crank arm whichis adapted to be operatively connected with the wiper and a crank shafteccentrically and rotatably supported by said drive member; shiftablemeans including a piston slidable on said drive shaft and slidablysupported by said housing means, said shiftable means being movablebetween a first position in which it engages said crank assembly to lockthe same against rotation relative to said drive shaft so that the crankassembly rotates with the drive shaft about the axis of the latter and asecond position in which it effects rotation of the crank assemblyrelative to the drive shaft to increase the throw of the crank assemblyin response to continued rotationof said drive member; and meansincluding means for creating a differential fluid pressure across thepiston for holding the shiftable means in its first position duringrunning operationand for moving the shiftable means to its secondposition when wiper operation is being terminated and the wipers are intheir inboard position to increase the throw of the crank arm andthereby move the wipers to. their park position. i

2. An actuating mechanism for use in oscillating a pair of windshieldwipers across a windshield between inboard and outboard positions duringrunning operation and for moving the wipers to a depressed park positionspaced from the inboard position when wiper operation'is beingterminated comprising: a housing means; an annular drive memberrotatably supported by said housing means; a drive shaft supported bysaid housing means for rotation about its axis and drivingly connectedwith said drive member; drive means operatively connected with saiddrive shaft for rotating the same and said drive member; a crankassembly including a crank arm which is adapted to be connected withsaid wipers and crank shaft eccentrically and rotatably supported bysaid drive member; shiftable means including piston means slidable onsaid drive shaft and slidably supported by said housing means and anelement slidable on said drive shaft, biasing means for biasing saidelement into engagement with said piston and said element and pistontowards a first position in which said element engages a second elementconnected to said crank shaft to lockthe drive and crank shafts againstrotation relative to each other and to .rotate said crank assembly aboutthe axis of the drive shaft; control means including means for creatinga differential fluid pressure across the piston to move said shiftablemeans from its first position towards a second position in which thefirst and second elements are disengaged from each other and in whichmeans carried by the piston is cooperably engageable with means on thesecond element to effect rotation of the crank shaft in a directionopposite the direction of rotation of the annular member while theannular member continues to rotate through a predetermined angularextent to'effect an increase in the throw of the crank arm, said controlmeans being operable to allow said biasing means to move said shiftablemeans to its first position during running operation of the wiper andbeing operable to move said shiftable means towards its second positionupon wiper operation being terminated and the wiper reaching its inboardposition to effect an increase in the inboard and outboard positionsduring running operation and for moving the wiper to a depressed parkposition spaced from the inboard position when wiper operation is beingterminated comprisin a housin means; an annular drive member rotatabfysupporte by said housing means; a drive shaft supported by said housingmeans for rotation about its axis and drivingly connected with saiddrive member; a drive means operatively connected with said drive shaftfor rotating the same and said drive member; a crank assembly includinga crank arm which is adapted to be operatively connected with saidwipers and which is eccentrically and rotatably supported by said drivemember; a piston slidable on said drive shaft and slidably supported bysaid housing; said piston having a plurality of axially extending postsat equally spaced angular locations on its side facing said annulardrive member, a partial ring member secured to all but one of said postsat its end remote from the piston and with the adjacent ends of thepartial ring defining a gap, a member which is both drivingly connectedwith said drive shaft and slidably supported thereon for linear movementtherealong, a spring means having one end in abutting engagement withsaid annular drive member and its other end in abutting engagement withsaid element, said crank shaft being drivingly connected to a genevawheel having alternately spaced lobes and recesses and with one of thelobes having a recessed periphery which is adapted to mate with arecessed peripheral portion of said element, said piston on its sideremote from said drive member being vented to the atmosphere and on itsopposite side being in communication with a vacuumv source, said springmeans biasing said piston and element toward a first position when nodifferential pressure exists across the piston and in which the recessedlobe of said geneva wheel is received within the recessed peripheralportion of said element to drivingly connect said geneva wheel with saidelement to effect rotation of said crank shaft with said drive shaftabout the axis of the drive shaft, said piston and element beingshiftable from their first position toward a second position inopposition to the biasing force of the spring when a differentialpressure is applied across the piston and in which the elementdisengages itself from the geneva wheel and the post not connected tosaid ring engages one of the slots in the geneva wheel when wiperoperation is being terminated, said partial ring being engageable withone side of said geneva wheel to prevent movement of said piston andelement toward their second position until the wipers are in theirinboard position at which time the geneva wheel will be disengaged fromthe ring to enable the piston and element to be moved towards theirsecond position and at which time the post not connected to the ringwill engage the slot of the geneva wheel to begin effecting rotation ofthe geneva wheel, which in turn will rotate the crank arm in thedirection opposite the direction of the rotation of the drive member toincrease the throw of the crank and move the wipers from their inboardposition to their park position.

1. An actuating mechanism for use in oscillating a windshield wiperacross the windshield between inboard and outboard positions duringrunning operation and for moving the wiper to a park position spacedfrom the inboard position when wiper operation is being terminatedcomprising: a housing means; an annular drive member rotatably supportedby said housing means; a drive shaft supported by said housing means forrotation about its axis and drivingly connected to said drive member; adrive means operatively connected with said drive shaft for rotating thesame and said drive member; a crank assembly including a crank arm whichis adapted to be operatively connected with the wiper and a crank shafteccentrically and rotatably supported by said drive member; shiftablemeans including a piston slidable on said drive shaft and slidablysupported by said housing means, said shiftable means being movablebetween a first position in which it engages said crank assembly to lockthe same against rotation relative to said drive shaft so that the crankassembly rotates with the drive shaft about the axis of the latter and asecond position in which it effects rotation of the crank assemblyrelative to the drive shaft to increase the throw of the crank assemblyin response to continued rotation of said drive member; and meansincluding means for creating a differential fluid pressure across thepiston for holding the shiftable means in its first position duringrunning operation and for moving the shiftable means to its secondposition when wiper operation is being terminated and the wipers are intheir inboard position to increase the throw of the crank arm andthereby move the wipers to their park position.
 2. An actuatingmechanism for use in oscillating a pair of windshield wipers across awindshield between inboard and outboard positions during runningoperation and for moving the wipers to a depressed park position spacedfrom the inboard position when wiper operation is being terminatedcomprising: a housing means; an annular drive member rotatably supportedby said housing means; a drive shaft supported by said housing means forrotation about its axis and drivingly connected with said drive member;drive means operatively connected with said drive shaft for rotating thesame and said drive member; a crank assembly including a crank arm whichis adapted to be connected with said wipers and crank shafteccentrically and rotatably supported by said drive member; shiftablemeans including piston means slidable on said drive shaft and slidablysupported by said housing means and an element slidable on said driveshaft, biasing means for biasing said element into engagement with saidpiston and said element and piston towards a first position in whichsaid element engages a second element connected to said crank shaft tolock the drive and crank shafts against rotation relative to each otherand to rotate said crank assembly about the axis of the drive shaft;control means including means for creating a differential fluid pressureacross the piston to move said shiftable means from its first positiontowards a second position in which the first and second elements aredisengaged from each other and in which means carried by the piston iscooperably engageable with means on the second element to effectrotation of the crank shaft in a direction opposite the direction ofrotation of the annular member while the annular member continues torotate through a predetermined angular extent to effect an increase inthe throw of the crank arm, said control Means being operable to allowsaid biasing means to move said shiftable means to its first positionduring running operation of the wiper and being operable to move saidshiftable means towards its second position upon wiper operation beingterminated and the wiper reaching its inboard position to effect anincrease in the throw of the crank arm to move the wipers to their parkposition prior to de-energizing the drive means.
 3. An actuatingmechanism for use in oscillating a pair of windshield wipers across awindshield between inboard and outboard positions during runningoperation and for moving the wiper to a depressed park position spacedfrom the inboard position when wiper operation is being terminatedcomprising: a housing means; an annular drive member rotatably supportedby said housing means; a drive shaft supported by said housing means forrotation about its axis and drivingly connected with said drive member;a drive means operatively connected with said drive shaft for rotatingthe same and said drive member; a crank assembly including a crank armwhich is adapted to be operatively connected with said wipers and whichis eccentrically and rotatably supported by said drive member; a pistonslidable on said drive shaft and slidably supported by said housing;said piston having a plurality of axially extending posts at equallyspaced angular locations on its side facing said annular drive member, apartial ring member secured to all but one of said posts at its endremote from the piston and with the adjacent ends of the partial ringdefining a gap, a member which is both drivingly connected with saiddrive shaft and slidably supported thereon for linear movementtherealong, a spring means having one end in abutting engagement withsaid annular drive member and its other end in abutting engagement withsaid element, said crank shaft being drivingly connected to a genevawheel having alternately spaced lobes and recesses and with one of thelobes having a recessed periphery which is adapted to mate with arecessed peripheral portion of said element, said piston on its sideremote from said drive member being vented to the atmosphere and on itsopposite side being in communication with a vacuum source, said springmeans biasing said piston and element toward a first position when nodifferential pressure exists across the piston and in which the recessedlobe of said geneva wheel is received within the recessed peripheralportion of said element to drivingly connect said geneva wheel with saidelement to effect rotation of said crank shaft with said drive shaftabout the axis of the drive shaft, said piston and element beingshiftable from their first position toward a second position inopposition to the biasing force of the spring when a differentialpressure is applied across the piston and in which the elementdisengages itself from the geneva wheel and the post not connected tosaid ring engages one of the slots in the geneva wheel when wiperoperation is being terminated, said partial ring being engageable withone side of said geneva wheel to prevent movement of said piston andelement toward their second position until the wipers are in theirinboard position at which time the geneva wheel will be disengaged fromthe ring to enable the piston and element to be moved towards theirsecond position and at which time the post not connected to the ringwill engage the slot of the geneva wheel to begin effecting rotation ofthe geneva wheel, which in turn will rotate the crank arm in thedirection opposite the direction of the rotation of the drive member toincrease the throw of the crank and move the wipers from their inboardposition to their park position.